1. Field of the Invention
The present invention relates to the art of electrical connectors, and more particularly to a connector contact for connecting a chip module to a printed circuit board.
2. Description of the Related Art
Generally speaking, a connector to which this invention is applicable is interposed between first and second electronic parts or components having contact pads, respectively, to achieve electrical connection between the first and the second electronic components. In the following description, the first and the second electronic components are a printed board and an LSI circuit, respectively.
Referring to FIGS. 1-4, a conventional connector, referring to No. U.S. Pat. 6,447,304, comprises a housing 10, a plurality of contacts 20 received in the housing 10.
Referring to FIGS. 1 and 2, each contact 20 is formed by punching and bending an elastic metal plate so that each contact 20 comprises a generally U-shaped portion comprising a first leg portion 21, a second leg portion 22 and a bridge portion 23 connecting the first and the second leg portions 21 and 22, and an extension portion 24 from obliquely extending an end 21a of the first leg portion 21 downwardly. The first leg portion 21 has the lower end 21a and a bent depression 21b above and adjacent the lower end 21a. The second leg portion 22 has a widened end 22a. The extension portion 24 has a curved end portion 24a as an extended lower end portion and a first contact point 24b formed on the curved end portion 24a to be brought into contact with the contact pad of the printed board 100. The bridge portion 23 has a second contact point 23a on its top portion to be brought into contact with the contact pad of the LSI circuit 200.
The holding effect of the contact by the wall surface is achieved because the contact 20 having a dimension a (FIG. 2) in a free state and having an elasticity is press-fitted into the contact receptacle hole 11 having a dimension A (FIG. 3) smaller than the dimension a. In addition, the holding portion 11a is inserted into the bent depression 21b, while the widened end 22a of a special shape is engaged with step portions at the holding portion 11b in the contact receptacle hole 11, as illustrated in FIG. 4.
Referring to FIGS. 3 and 4, the contact 20 is inserted into each of the contact receptacle holes 11 of the insulator 10 and held at a predetermined position. In this state, the first and the second leg portions 21 and 22 are held by an inner wall surface of the contact receptacle hole 11. Specifically, the end portion of the first leg portion 21 including the lower end 21a and the bent depression 21b and the end portion of the second leg portion 22 including the widened end 22a are respectively held by holding portions 11a and 11b each of which is a part of the inner wall surface defining the contact receptacle hole 11. The end portions of the first and the second leg portions 21 and 22 may be referred to as supported portions.
As seen from FIG. 3, the contact receptacle hole 11 of the insulator 10 has a cavity 11c and a depression 11d. The cavity 11c should be understood as a recess formed in a lower surface of the insulator 10 to allow elastic deformation of the extension portion 24 of the contact 20 inserted into the contact receptacle hole 11. Likewise, the depression 11d should be understood as a recess formed in the inner wall of the contact receptacle hole 11 to allow elastic deformation of the first and the second leg portions 21 and 22 together with the bridge portion 23 of the contact 20 inserted into the contact receptacle hole 11.
A problem, however, with using the connector contact 20 is that, the connector contact 20 may be subjected to premature fatigue at the leg portions 21, 22 after depressing for many times. This is prone to produce a loose engagement between the contact 20 and the contact receptacle hole 102 result in contact 20 is easy to escape from the contact receptacle hole 11.